Validation issues for user names and passwords in C #.

The purpose of this exercise is to use LINQ to XML, regular expressions, to practice using serialization and deserialization on this basis tomorrow, and continue to add a little bit of functionality.

First, this is a form program, designed as follows:

The XML that holds the user name and password is as follows:

The implementation code is as follows:

1 usingSystem;2 usingSystem.Collections.Generic;3 usingSystem.ComponentModel;4 usingSystem.Data;5 usingSystem.Drawing;6 usingSystem.Linq;7 usingSystem.Text;8 usingSystem.Threading.Tasks;9 usingSystem.Windows.Forms;Ten usingSystem.Text.RegularExpressions; One usingSystem.Xml; A usingSystem.Xml.Linq; -  - namespaceCheckinfo the { -      Public Partial classForm1:form -     { -          PublicForm1 () +         { - InitializeComponent (); +         } A  at         Private voidtextBox1_TextChanged (Objectsender, EventArgs e) -         { -             if(TextBox1.Text = ="Please enter user name, format: Qarootdc\\jqhuang") -             { -TextBox1.Text =""; -             } in  -         } to  +         Private voidTextbox2_textchanged_1 (Objectsender, EventArgs e) -         { the             if(TextBox2.Text = ="Please enter your password") *             { $TextBox2.Text ="";Panax Notoginseng             } -         } the  +         Private voidButton1_Click (Objectsender, EventArgs e) A         { the             if(IsValidUserName (textbox1.text) = =false) +             { -MessageBox.Show ("user name is not properly formatted! Please re-enter! "); $TextBox1.Text =""; $             } -             Else  -             { the                 //The user name is formatted correctly. - checkuserandpwd (textbox1.text,textbox2.text);Wuyi             } the         } -  Wu         Private voidCheckuserandpwd (stringUsernamestringpwd) -         { About             //read Userinfo.xml detect if user exists $XDocument UserInfo = Xdocument.load (@"C:\Users\jqhuang\Desktop\UserInfo.xml"); -             varresult = fromUserelementinchUserinfo.element ("System"). Element ("Users"). Elements ()whereUserelement.element ("username"). value.tostring () = = TextBox1.Text.ToString ()SelectUserelement.element ("pwd"). Value; -             if(Result! =NULL) -             { A                 foreach(varPasswordinchresult) +                 { the                     if(Password = =pwd) -                     { $MessageBox.Show ("user name and password match successfully! "); the                     } the                     Else the                     { theMessageBox.Show ("user name and password do not match, please re-enter the password"); -TextBox2.Text =""; in                     } the                 } the             } About             Else  the             { theMessageBox.Show ("the user you entered does not exist! "); the             } +         } -  the         BOOLIsValidUserName (stringuserName)Bayi         { the             returnRegex.IsMatch (UserName,@"^.+\\.+$"); the         } -     } -}

Run as follows--

1, the user name does not exist in the case:

/

2, the user name and password does not match the situation:

3, the user name format is not correct (with regular expression validation):

4, the user name and password matching successful situation:

Validation issues for user names and passwords in C #.